NEW YORK (AP) -- Scientists have identified a hormone that can sharply boost the number of cells that make insulin in mice, a discovery that may someday lead to a treatment for the most common type of diabetes.

People have their own version of this hormone, and the new work suggests that giving diabetics more might one day help them avoid insulin shots.

That would give them better control of their blood sugar levels, said Harvard University researcher Douglas Melton, senior author of a report published Thursday by the journal Cell.

Experts unconnected with the work cautioned that other substances have shown similar effects on mouse cells but failed to work on human ones. Melton said this hormone stands out because its effect is unusually potent and confined to just the cells that make insulin.

An estimated 371 million people worldwide have diabetes, in which insulin fails to control blood sugar levels. High blood sugar can lead to heart disease, stroke and damage to kidneys, eyes and the nervous system. At least 90 percent of diabetes is "Type 2," and some of those patients have to inject insulin. Melton said the newly identified hormone might someday enable them to stop insulin injections and help other diabetic patients avoid them.

As for its possible use to treat Type 1 diabetes, Melton called that a "long shot" because of differences in the biology of that disease.

Insulin is produced by beta cells in the pancreas.

Melton and co-authors identified a hormone they dubbed betatrophin (BAY-tuh-TROH-fin) in mice. When they made the liver in mice secrete more of it by inserting extra copies of the gene, the size of the beta cell population tripled in comparison to untreated mice. Tests indicated the new cells worked normally.

Melton said it's not known how the hormone works. Now the researchers want to create an injectable form that they can test on diabetic mice, he said. If all goes well, tests in people could follow fairly quickly.

Dr. Peter Butler, a diabetes researcher at the University of California, Los Angeles, who had no role in the new work, cautioned in an email that no evidence has been presented yet to show that the hormone will make human beta cells proliferate.

But Philip diIorio, of the University of Massachusetts Medical School in Worcester, said he found the work to be "quite promising" because it offers new leads for research, and that it might someday help in building supplies of human beta cells in a lab for transplant into patients.